Dual FAI Configurations

[Itamar Gal]

Hey John,

Thank you for the helpful response.

> it is hard to say what you need to do without knowing specifically what
> problems you are having.

One thing that I really want to be able to do (beyond solving my
immediate problems) is figure out a good way to debug and experiment
with FAI without stepping on anyone's toes or interfering with the
active/production system. For some kinds of testing I've successfully
used chroot and fai dirinstall and for other kinds of testing I've
used VirtualBox VMs, but it would be nice to also be able to test
things out on hardware with the actual install clients.

That said, I think you're right - my question might be too general. I
might post a different message with a specific error.

> What you want to do probably isn't that different
> than what we all have to deal with when upgrading our FAI configuration for
> a new release of our chosen linux flavor. I'm currently switching from
> Ubuntu zesty to artful and I need to make sure that the zesty install keeps
> working while I build the artful configuration.

Could be - I'm still very new to FAI. I haven't had to deal with an upgrade yet.

> What I do is to create a class for the new configuration and put changes in
> files named for that class. So for example, if artful requires some changes
> to the contents of /etc/networking/interfaces, I create a file named ARTFUL
> within the fai config for a new version of that file. This is generally
> sufficient for all modifications. In fact, doing anything more drastic, like
> making a copy of the entire config space, only makes it harder to eventually
> integrate the changes into the production space.
>
> So my first recommendation would be to try to use FAI's class feature to do
> your experiments. But if you want to create a whole nother config space, you
> can tell your FAI clients about it by setting the boot parameter,
> FAI_CONFIG_SRC in the pxe boot config file. I manually generate my own pxe
> boot config files instead of using fai-chboot. Just never got the hang of
> it. So what I'd do if I wanted to experiment with a whole nother config on a
> machine or two would be this:
>
> 1. Make a copy of the FAI config space. Say, from the default
> /srv/fai/config/ to /opt/fai/config/.
> 2. Make whatever changes I needed to the files in /opt/fai/config/.
> 3. Create pxe boot config files for selected machines.
> 4. In the custom pxe boot file, change
> FAI_CONFIG_SRC=nfs://faiserver/srv/fai/config to
> FAI_CONFIG_SRC=nfs://faiserver/opt/fai/config.
>
> It might not be obvious how to do step #3.   When you pxe boot a machine, it
> first asks the server for a machine matching it's own MAC addres.s Then it
> asks for a file matching it's own IP address in hexadecimal. Then it asks
> for a file matching the first 7 characters of it's IP address. Then 6, etc.
> If you know the MAC or IP address of the machines you are experimenting
> with, you create a file within your pxe boot config space for those
> addresses. I am unclear on the format for using MAC address but for IPV4
> addresses, it's IP address quad format in hexadecimal. So for example, if
> you want to make a custom pxe boot file for a machine with the IPV4 address
> of 128.64.32.16, it would be 80402010.  You can make a custom pxe boot file
> for any machine with an IP address in the range, 128.64.32.0/24 by creating
> a file named 804020.

Thanks for the advice. I'll give this approach a try.

> PS: You probably don't need to create a second nfsroot.

I believe you that this is true in general, but I think that I may
actually also want to poke at the nfsroot a little bit.

Thanks again for the response.

- Itamar